The present invention relates to a light distribution device and more particularly to a device which is able to receive light transmitted through a single light-guiding cable and to time-sharingly distribute the same to a large number of light-guiding cables. More concretely, the present invention relates to a device which is capable of effectively supplying light necessary for the photosynthesis of living organisms such as algae, (for example, chlorella, spirulina etc.), photosynthesized bacteria and other artificially photosynthesized substances as for example callus and such living things as plants, mushrooms etc.
A chlorella culturing device, as an example of a photosynthetic reactor, has been proposed in which chlorella is cultured by feeding it with light and carbon dioxide for aiding in the process of photosynthesis. However, as a result of some detailed research into the phtosynthetic process it has been found that one cycle of phtosynthetic reaction in chlorella requires an instant light radiation duration of about 10 microseconds and the rest duration about 200 microseconds therein photosynthetic reaction can be conducted without light radiation, more exactly, the reaction can be more effectively conducted with no light radiation for the rest duration of the cycle. On the other hand, in the case of chlorella culturing it is usual to use such a phtosynthetic reactor (for instance, a chlorella culturing bath) wherein a large number of fluorescent lamps are arranged so as to allow photosynthetic substances to pass through the gaps between the lamps. Said conventional bath, due to the use of a large number of fluorescent lamps, is large and requires the consumption of much electricity. Furthermore it necessitates strong treatment of heat generated by the lamps. To solve these problems, the present applicant has previously proposed that solar rays or artificial rays be focused and introduced into a fiber optic cable and then transmitted therethrough to a light radiator which is used as a light source for a photosynthetic reactor. However, it is also evident that when a large scale photosynthetic reactor is constructed with the use of the above-mentioned light-radiating means, a large number of light radiators must be used or a large-sized device for focusing the sun's rays and/or artificial light rays is necessary.
To solve the above-mentioned problems, the present applicant has also proposed a light distribution device which is able to intermittently supply light energy to photosynthetic substances in order to more effectively promote the process of photosynthesis and therefore is sufficient to cover the need for light energy for any large-scale photosynthetic reactor at the fixed capacity of a solar ray and/or artificial light ray focusing device.
A photosynthetic reactor's light source previously proposed by the present applicant has a light-guiding rod or a light-guiding cable for transmitting solar rays or artificial light rays focused by lenses (not shown) and a transparent rotary rod. The light-emitting end of the light guide is placed opposite the rotating axis of the rotary rod, and a reflecting mirror is provided at the rotating axis of the rotary rod against the light-emitting end of the light guide. The light transmitted through the light guide and introduced into the rotary rod is reflected a the mirror and propagates toward the tip portion of the rotary rod, whereas the light is reflected again by a mirror provided thereat and then radiated out from the light-emitting surface of the rotary rod. A large number of light-guiding rods are arranged to form a ring, placed opposite to the light-emitting surface of the rotary rod. Consequently, when the rotary rod is rotated by a motor, the light-receiving faces of the light-guiding rods to be covered with the light-emitting surface of the rotary rod are changed in turn and each light-guiding rod receives an instant burst of light radiation for each rotation. The end portion of each light-guiding rod serves as a light radiator. The light radiators may be provided at a certain distance from each other in a photosynthetic reactor, or widely spread apart in a plant-cultivating room, a mushroom cultivating place and so on.
As described above, in the light-distribution device provided previously by the present applicant the light delivered thereto through the light guide is supplied momentarily into the light guides and in turn through the rotary rod being rotated and, accordingly, the distributed light is discharged momentarily from the output end of each light-guiding rod, once for each rotation of the rotary rod into a photosynthetic reactor wherein a photosynthetic substance is radiated with the light for a very short period, for instance about 10 microseconds and then initiates a cycle of a photosynthetic reaction and completes the cycle without the need for additional light radiation, and then at the next burst of light radiation, through one rotation of the rotary rod, it initiates a new cycle of photosynthetic reaction. A series of photosynthetic reactions in the reactor is thus continued with periodical light radiation of photosynthetic substances. For initiating the photosynthesis of the object it is necessary to supply no less than a specified amount of light energy. In the above-mentioned light distribution device a necessary amount of light energy may be easily obtained by increasing the density of the light for a very small area corresponding to the light-emitting surface of the rotary rod. Thanks to this construction feature, the device can work well with a compact solar ray or artificial light ray collecting device. Furthermore, since the light discharged from the light-emitting surface of the rotary rod is time-sharingly distributed to many light-guiding rods, the device can supply a sufficient amount of light energy into a photosynthetic reactor of a large capacity.
However, the above-mentioned light distribution device has some drawbacks in that the rotary rod is difficult to make and is expensive.